To connect the Moxa with my apus I had to customize the cables I got from aliexpress.
Till now I never had to create my custom serial console cable, so to me this was a new experience.
Finding the combination
I first had to find out the correct combination of cables since it did not work with these cables right away so I put a breadboard in between the cables. To connect the wires to the breadboard I did crimp connectors to them. For this I used a crimping tool and a set of connectors. Then the fun started, based on the information from pcengines and from the Moxa CN2510 Manual about the expected wiring I tried to apply it to the existing cable.
Check the cable
Finally I had the correct wiring transferred to my cable.
For the RJ45 the Moxa needs the following wiring:
From the DB9 Connector these colors are assigend to the follwing Pins, the apu expects a wiring of a null modem cable.